Also, what are the consequences of spinning down for the lifetime of
my laptop's hdd (hitachi 20gb)? Is this good for it or does it take a
toll? I understand that it saves energy, but what's the toll on the
overall computer life? I heard some hdds only have a number of spin
downs in their lifespan.

Well, for what it's worth, I believe the BIOS default of my Dell laptop
was something like a 5 minute wait before spindown on the hard disk. But
then maybe that's why they are big on selling you those 3-4 year
warranty packages.

Yes, these things take a toll, but I don't think it is something that
you need to worry about.

Consider how many hours per day you will operating your laptop on
battery power. Probably, it will be something like 1-4 hours, yes? That
isn't very much in the greater scheme of things.

So, perhaps the best solution is to only enable a short spin down and
short screen lamp off time when you are on battery, and alter this
behavior for when you are running on AC.

Or perhaps you could purchase a second battery back instead, and set
your harddrive free to run as it likes.